There are three kinds of LED car brake light by its location, LED car tail brake light, LED car dashboard brake light and LED car third brake light.
Sockets of tail brake light:
BAY15D LED car tail bulb light is also called P21/5W or 1157, the structure of this kind of socket has a double-wire. This kind of LED car bulb owns the function of warning and position-indicating. When in the brake function, power is 21W; when in position-indicating function, power is 5W. Generally, the position-indicating function is open.
W21/5W(7443) has a double-wire, with warning function and position-indicating function. Power is 21W when in brake function and 5W when in position-indicating function. Position-indicating function is usually open.
P27/5W(3157), double-wire, with warning function and position-indicating function. Power is 27W when in brake function and 5W when in position-indicating function. Position-indicating function is usually open.
What’s the brake light used to? Rear brake light and third brake light are used to avoid the rear-end accident. Dashboard brake light is used to indicate when the rear brake light is lighting.